Replacing Part of Glucose with Galactose in the Postweaning Diet Protects Female But Not Male Mice from High-Fat Diet-Induced Adiposity in Later Life

Cow's Milk Bioactive Molecules in the Regulation of Glucose Homeostasis in Human and Animal Studies

Obesity disrupts glucose metabolism, leading to insulin resistance (IR) and cardiometabolic diseases. Consumption of cow's milk and other dairy products may influence glucose metabolism. Within the complex matrix of cow's milk, various carbohydrates, lipids, and peptides act as bioactive molecules to alter human metabolism. Here, we summarize data from human studies and rodent experiments illustrating how these bioactive molecules regulate insulin and glucose homeostasis, supplemented with in vitro studies of the mechanisms behind their effects. Bioactive carbohydrates, including lactose, galactose, and oligosaccharides, generally reduce hyperglycemia, possibly by preventing gut microbiota dysbiosis. Milk-derived lipids of the milk fat globular membrane improve activation of insulin signaling pathways in animal trials but seem to have little impact on glycemia in human studies. However, other lipids produced by ruminants, including polar lipids, odd-chain, trans-, and branched-chain fatty acids, produce neutral or contradictory effects on glucose metabolism. Bioactive peptides derived from whey and casein may exert their effects both directly through their insulinotropic effects or renin-angiotensin-aldosterone system inhibition and indirectly by the regulation of incretin hormones. Overall, the results bolster many observational studies in humans and suggest that cow's milk intake reduces the risk of, and can perhaps be used in treating, metabolic disorders. However, the mechanisms of action for most bioactive compounds in milk are still largely undiscovered.

The Effect of Broccoli Glucoraphanin Supplementation on Ameliorating High-Fat-Diet-Induced Obesity through the Gut Microbiome and Metabolome Interface

SCOPE

Obesity and its metabolic comorbidities pose a major global challenge for public health. Glucoraphanin (GRN) is a natural bioactive compound enriched in broccoli that is known to have potential health benefits against various human chronic diseases.

METHODS AND RESULTS

This study investigats the effects of broccoli GRN supplementation on body weight, metabolic parameters, gut microbiome and metabolome associated with obesity. The study is conducted on an obese-related C57BL/6J mouse model through the treatment of normal control diet, high-fat diet (HFD)and GRN-supplemented HFD (HFD-GRN) to determine the metabolic protection of GRN. The results shows that GRN treatment alleviates obesity-related traits leading to improved glucose metabolism in HFD-fed animals. Mechanically, the study noticed that GRN significantly shifts the gut microbial diversity and composition to an eubiosis status. GRN supplement also significantly alters plasma metabolite profiles. Further integrated analysis reveal a complex interaction between the gut microbes and host metabolism that may contribute to GRN-induced beneficial effects against HFD.

CONCLUSION

These results indicate that beneficial effects of broccoli GRN on reversing HFD-induced adverse metabolic parameters may be attributed to its impacts on reprogramming microbial community and metabolites. Identification of the mechanistic functions of GRN further warrants it as a dietary candidate for obesity prevention.

Dietary Galactose Increases the Expression of Mitochondrial OXPHOS Genes and Modulates the Carbohydrate Oxidation Pathways in Mouse Intestinal Mucosa

BACKGROUND

Prolonged lactation provides substantial health benefits, possibly because of galactose as part of milk sugar lactose. Isocaloric replacement of dietary glucose [16 energy%(en%)] with galactose within a normal diet (64en% carbohydrates) during a 3-wk postweaning period provided substantial benefits on short- and long-term physiologic and metabolic parameters at the whole-body level and liver in female mice, which might be attributable to intestinal function.

OBJECTIVES

This study aimed to investigate if partial dietary replacement of glucose with galactose alters intestinal metabolism underlying hepatic health effects.

METHODS

Proximal intestinal mucosa gene profiles in female mice were analyzed using RNAseq technology, validated, and correlated with hepatic health parameters.

RESULTS

Transcriptome analysis revealed that the presence of galactose primarily affected the pathways involved in energy metabolism. A consistently higher expression was observed in the subset of mitochondrial transcripts (78 of 80, all P.adj < 0.1). Oxidative phosphorylation (OXPHOS) represented the most upregulated process (all top 10 pathways) independent of the total mitochondrial mass (P = 0.75). Moreover, galactose consistently upregulated carbohydrate metabolism pathways, specifically glycolysis till acetyl-CoA production and fructose metabolism. Also, the expression of transcripts involved in these pathways was negatively correlated with circulating serum amyloid A3 protein, a marker of hepatic inflammation [R (-0.61, -0.5), P (0.002, 0.01)]. Accordingly, CD163+ cells were decreased in the liver. Additionally, the expression of key fructolytic enzymes in the small intestinal mucosa was negatively correlated with triglyceride accumulation in the liver [R (-0.45, -0.4), P (0.03, 0.05)].

CONCLUSIONS

To our knowledge, our results show for the first time the role of galactose as an OXPHOS activator in vivo. Moreover, the concept of intestinal cells acting as the body's metabolic gatekeeper is strongly supported, as they alter substrate availability and thereby contribute to the maintenance of metabolic homeostasis, protecting other organs, as evidenced by their potential ability to shield the liver from the potentially detrimental effects of fructose.

Health relevance of lowering postprandial glycaemia in the paediatric population through diet': results from a multistakeholder workshop

To summarize current knowledge and gaps regarding the role of postprandial glycaemic response in the paediatric population, a workshop was organized in June 2021 by the European branch of the International Life Science Institute (ILSI). This virtual event comprised of talks given by experts followed by in-depth discussions in breakout sessions with workshop participants. The main pre-specified topics addressed by the workshop organizing committee to the invited speakers and the workshop participants were: (1) the role of glycaemic responses for paediatric health, based on mechanistic insights from animal and human data, and long-term evidence from observational and intervention studies in paediatric populations, and (2) changes in metabolism and changes in dietary needs from infancy to adolescence. Each talk as well as the discussions were summarised, including the main identified research gaps. The workshop led to the consensus on the crucial role on health of postprandial glycaemic response in paediatric population. However, a lack of scientific data has been identified regarding detailed glucose and insulin profiles in response to foods commonly consumed by paediatric populations, as well as a lack of long-term evidence including the need for suitable predictors during childhood and adolescence to anticipate health effects during adulthood.

Galactose in the Post-Weaning Diet Programs Improved Circulating Adiponectin Concentrations and Skeletal Muscle Insulin Signaling

Short-term post-weaning nutrition can result in long-lasting effects in later life. Partial replacement of glucose by galactose in the post-weaning diet showed direct effects on liver inflammation. Here, we examined this program on body weight, body composition, and insulin sensitivity at the adult age. Three-week-old female C57BL/6JRccHsd mice were fed a diet with glucose plus galactose (GAL; 16 energy% (en%) each) or a control diet with glucose (GLU; 32 en%) for three weeks, and afterward, both groups were given the same high-fat diet (HFD). After five weeks on a HFD, an oral glucose tolerance test was performed. After nine weeks on a HFD, energy metabolism was assessed by indirect calorimetry, and fasted mice were sacrificed fifteen minutes after a glucose bolus, followed by serum and tissue analyses. Body weight and body composition were not different between the post-weaning dietary groups, during the post-weaning period, or the HFD period. Glucose tolerance and energy metabolism in adulthood were not affected by the post-weaning diet. Serum adiponectin concentrations were significantly higher (p = 0.02) in GAL mice while insulin, leptin, and insulin-like growth factor 1 concentrations were not affected. Expression of Adipoq mRNA was significantly higher in gonadal white adipose tissue (gWAT; p = 0.03), while its receptors in the liver and skeletal muscles remained unaffected. Irs2 expression was significantly lower in skeletal muscles (p = 0.01), but not in gWAT or Irs1 expression (in both tissues). Gene expressions of inflammatory markers in gWAT and the liver were also not affected. Conclusively, galactose in the post-weaning diet significantly improved circulating adiponectin concentrations and reduced skeletal muscle Irs2 expression in adulthood without alterations in fat mass, glucose tolerance, and inflammation.

Investigation of Mitochondrial Adaptations to Modulation of Carbohydrate Supply during Adipogenesis of 3T3-L1 Cells by Targeted 1H-NMR Spectroscopy

(1) Background: White adipose tissue (WAT) is a dynamic and plastic tissue showing high sensitivity to carbohydrate supply. In such a context, the WAT may accordingly modulate its mitochondrial metabolic activity. We previously demonstrated that a partial replacement of glucose by galactose in a culture medium of 3T3-L1 cells leads to a poorer adipogenic yield and improved global mitochondrial health. In the present study, we investigate key mitochondrial metabolic actors reflecting mitochondrial adaptation in response to different carbohydrate supplies. (2) Methods: The metabolome of 3T3-L1 cells was investigated during the differentiation process using different glucose/galactose ratios and by a targeted approach using ¹H-NMR (Proton nuclear magnetic resonance) spectroscopy; (3) Results: Our findings indicate a reduction of adipogenic and metabolic overload markers under the low glucose/galactose condition. In addition, a remodeling of the mitochondrial function triggers the secretion of metabolites with signaling and systemic energetical homeostasis functions. Finally, this study also sheds light on a new way to consider the mitochondrial metabolic function by considering noncarbohydrates related pathways reflecting both healthier cellular and mitochondrial adaptation mechanisms; (4) Conclusions: Different carbohydrates supplies induce deep mitochondrial metabolic and function adaptations leading to overall adipocytes function and profile remodeling during the adipogenesis.

Influence of Nutritional Intake of Carbohydrates on Mitochondrial Structure, Dynamics, and Functions during Adipogenesis

Obesity is an alarming yet increasing phenomenon worldwide, and more effective obesity management strategies have become essential. In addition to the numerous anti-adipogenic treatments promising a restauration of a healthy white adipose tissue (WAT) function, numerous studies reported on the critical role of nutritional parameters in obesity development. In a metabolic disorder context, a better control of nutrient intake is a key step in slowing down adipogenesis and therefore obesity. Of interest, the effect on WAT remodeling deserves deeper investigations. Among the different actors of WAT plasticity, the mitochondrial network plays a central role due to its dynamics and essential cellular functions. Hence, the present in vitro study, conducted on the 3T3-L1 cell line, aimed at evaluating the incidence of modulating the carbohydrates intake on adipogenesis through an integrated assessment of mitochondrial structure, dynamics, and functions-correlated changes. For this purpose, our experimental strategy was to compare the occurrence of adipogenesis in 3T3-L1 cells cultured either in a high-glucose (HG) medium (25 mM) or in a low-glucose (LG) medium (5 mM) supplemented with equivalent galactose (GAL) levels (20 mM). The present LG-GAL condition was associated, in differentiating adipocytes, to a reduced lipid droplet network, lower expressions of early and late adipogenic genes and proteins, an increased mitochondrial network with higher biogenesis marker expression, an equilibrium in the mitochondrial fusion/fission pattern, and a decreased expression of mitochondrial metabolic overload protein markers. Therefore, those main findings show a clear effect of modulating glucose accessibility on 3T3-L1 adipogenesis through a combined effect of adipogenesis modulation and overall improvement of the mitochondrial health status. This nutritional approach offers promising opportunities in the control and prevention of obesity.

The Importance of Lactose in the Human Diet: Outcomes of a Mexican Consensus Meeting

Lactose is a unique component of breast milk, many infant formulas and dairy products, and is widely used in pharmaceutical products. In spite of that, its role in human nutrition or lactose intolerance is generally not well-understood. For that reason, a 2-day-long lactose consensus meeting with health care professionals was organized in Mexico to come to a set of statements for which consensus could be gathered. Topics ranging from lactase expression to potential health benefits of lactose were introduced by experts, and that was followed by a discussion on concept statements. Interestingly, lactose does not seem to induce a neurological reward response when consumed. Although lactose digestion is optimal, it supplies galactose for liver glycogen synthesis. In infants, it cannot be ignored that lactose-derived galactose is needed for the synthesis of glycosylated macromolecules. At least beyond infancy, the low glycemic index of lactose might be metabolically beneficial. When lactase expression decreases, lactose maldigestion may lead to lactose intolerance symptoms. In infancy, the temporary replacing of lactose by other carbohydrates is only justified in case of severe intolerance symptoms. In those who show an (epi)genetic decrease or absence of lactase expression, a certain amount (for adults mostly up to 12 g per portion) of lactose can still be consumed. In these cases, lactose shows beneficial intestinal-microbiota-shaping effects. Avoiding lactose-containing products may imply a lower intake of other important nutrients, such as calcium and vitamin B12 from dairy products, as well as an increased intake of less beneficial carbohydrates.

Partial replacement of glucose by galactose in the post-weaning diet improves parameters of hepatic health

Replacing part of glucose with galactose in the post-weaning diet beneficially affects later life metabolic health in female mice. The liver is the main site of galactose metabolism, but the direct effects of this dietary intervention on the liver in the post-weaning period are not known. The aim of this study was to elucidate this. Weanling female mice (C57BL/6JRccHsd) were fed a starch containing diet with glucose (32 en%) monosaccharide (GLU), or a diet with glucose and galactose (1:1 both 16 en%) (GLU+GAL). Body weight, body composition, and food intake were determined weekly. After 3 weeks, mice were sacrificed, and serum and liver tissues were collected. Global hepatic mRNA expression was analyzed and hepatic triglyceride (TG) and glycogen contents were determined by enzymatic assays. Body weight and body composition were similar in both groups, despite higher food intake in mice on GLU+GAL diet. Hepatic TG content was lower in GLU+GAL-fed than GLU-fed females, while glycogen levels were unaffected. Analysis of global expression patterns of hepatic mRNA showed that mainly inflammation-related pathways were affected by the diet, which were predominantly downregulated in GLU+GAL-fed females compared to GLU-fed females. This reduction in inflammation in GLU+GAL-fed females was also reflected by decreased serum concentrations of acute phase protein Serum amyloid A 3. In conclusion, replacing part of glucose with galactose in the post-weaning diet reduces hepatic TG content and hepatic inflammation.